Many LED lighting applications require heat sinks to dissipate heat from the LEDs. In order to ensure a long service life of LED modules, it is important to lead away the generated heat.
In most applications which combine LEDs with heatsinks, the LED module or modules are mounted on a heat sink, or else they are mounted on a printed circuit board (PCB) which itself is fixed to the heat sink. The LED module or LED PCB is connected to the heat sink through intermediate materials that are in direct contact at their interfaces. For example, solder materials or thermal interface materials bridge the interface avoiding any air gap, in order to facilitate heat transfer from the LED to the heat sink. The generated heat is led to the heat sink through this interface, and then passes to the surroundings for example by fins of the heat sink.
LEDs, and in particular high power LEDs, have a limited lifetime. There may therefore be a need to replace the LEDs. For LED modules directly mounted to a heat sink, this involves replacing the heat sink. For LED modules mounted on a PCB, it may for example involve removing the LED PCB from the heat sink, and replacing the LED PCB as a single component. The LEDs and their PCB may then be considered to be a single unit.
A problem arises that this operation is not straightforward. In particular, the thermal interface material needs to be replaced. This may for example comprise a gel material. The LED replacement then should not be carried out by the public but needs to be conducted by specialists. Contamination of the LED by the thermal interface material will adversely affect the light output and the reliability of the LED in an undesired manner. The alternative of exchanging the LED together with the heat sink results in unacceptably high cost to the customer.
There is therefore a need for an LED module which can easily be changed without the expense of replacing the heat sink. Such need has in part been addressed in the prior art of e.g. WO2012048351A1, JP2011181418A, WO2014083122A1, US20120293652A1, WO2010044011A1, and US20110019409A1 by introducing modular concepts for the heat sink, i.e., mounting the LEDs on a first part of a multi-part heat sink which first part is detachably fastened to the remaining part of the multi-part heat sink. The construction of such multi-part heat sinks, however, leaves further room for improvement.